This invention relates to a countermeasures system for detecting and diverting an attacking unit.
When penetrating enemy territory under conditions of limited warfare, bombers suffer attack from enemy aircraft vectored by radar. These aircraft attack the bombers with air-to-air missiles which employ both microwave and infrared homing systems. Currently bombers of this class have increased their penetration capability by employing electronic countermeasures system to deny the attacking missiles accurate radar position data. In the past, infrared countermeasures systems have been employed in an attempt to deceive infrared homing systems by employing the use of flares or decoys, which provide the homing system with an incorrect angle of attack. These approaches suffer shortcomings such as having an insufficient power in the right portion of the spectrum and lacking a sufficient duration of burning time coupled with inherent break-away problems from the launching aircraft to be defended. Other problems have been encountered with the use of decoys because of their limited time of flight and the absence of an exact knowledge as when to launch, plus the over-all problem of carrying sufficient quantities of such decoys.
The purpose of this invention is to obviate the problems that have arisen in the prior art. This countermeasures systems is basically comprised of an enemy attack detection device which may be an active or passive system. The countermeasures system in responding to the presence of the attacking enemy produces a radiation as for example light which illuminates the attack unit, which, in turn, reflects a portion of the radiation. The reflected radiation is received by the countermeasures system, analyzed and information in signal form so received is used to control the characteristics of a radiation directed at the attack unit to thereby deceive the homing controls in the attack unit and divert the attack unit""s direction.
Specifically, the basic function of the system in a preferred embodiment is the location of an attacking aircraft which is the missile carrier by passive electronics countermeasures or infrared techniques followed by illumination of the attacking aircraft with a continual laser beam. The next step requires the examination of the frequency pattern of the light reflected from spinning reticule or scanner in the missile head while the missile is on the plane and the last step requires the modulation of the laser beam with the appropriate frequency pattern and phase shift so that a false target is seen by the missile. The missile, accordingly, will attack this false target when it is launched. As soon as it has turned sufficiently to move the false target out of its field of view, the missile will also have lost the airplane. Since it cannot reacquire and has limited turning rates, the missile will wander and appear erratic thus aborting its mission. The attacking aircraft being unable to see the modulated infrared laser beam will conclude that the missile was defective. It is therefore seen that this new system is capable of acting as a continuously operable countermeasures system capable of denying angular information to infrared seekers employing spinning reticule direction finding techniques.
An object of this invention, therefore, is to deceive homing type attacking missiles by illuminating the missile with a false target signal.
Another object of this invention is to deceive an aircraft carrying a missile into believing there has been some malfunction in the missile by using a target error signal which is invisible to the aircraft""s pilot.
Yet another object of this invention is to establish a compact countermeasures system incorporating a modulatable electromagnetic generator as a target error signal source.
Yet another object is to provide defense for aircraft against attacking missiles employing homing guidance as described that is completely automatic and does not require an operator.
Yet another object of this invention is to provide an efficient lightweight countermeasure system requiring relatively low power drain from the aircraft power supply uniquely adapting it for airborne use.
Yet another object of this invention is to provide angle deception for passive guidance systems of the type generally known to those skilled in the art as LORO (lobe on receive only).